Preface to the English Edition. 



IT is more than three years since Abderhalden first 

 published his results in regard to the sero-diagnosis 

 of pregnancy. In the course of his general studies 

 on the nature and properties of the ferments in the 

 blood, and on their relations to metabolism, he came 

 across an instance of their specific action, which 

 suggested the possibility of diagnosing the condition 

 of pregnancy by their means. And it was on the 

 basis of the same methods as had been employed 

 years before by himself and his followers in their 

 preliminary theoretical investigations, that he was 

 led to the great discovery of the demonstration of 

 specific ferments in the blood-serum ; that is to say, 

 by the use of the optical method and of the dialysation 

 process. 



In view of the possibility of the practical appli- 

 cation, in medicine, of these new methods of research, 

 for the purpose of making differential diagnoses and 

 of testing the functions of organs in various diseases, 

 they have been taken up by many members of the 

 medical profession. They were first employed by the 

 gynaecologist ; but there is now hardly any branch 

 of medicine left in which the application of these new 

 methods has not been attempted, and in the course 



